Earth's dismal water future, mapped

Satellite data and images are provocative, even disturbing. They confront us with a global view that can be at once breathtaking, like a piece of art, and yet, in this era of rapidly changing climate, they paint a picture of the demise of the environment. How and if we will respond to what we see is uncertain. That uncertainty lies at the root of our perilous future.

Last month, my colleagues and I published a report the centerpiece of which is a global map, derived from satellite data, that shows how the distribution of Earth’s fresh water has rapidly changed since 2002. We analyzed measurements from NASA’s Gravity Recovery and Climate Experiment satellites to determine trends in total water storage — groundwater, soil moisture, surface waters, snow and ice — over nearly a decade and half.

Although the map is strikingly simple — color coded from blue to red to show average increases and decreases per year in available fresh water — the story it reveals is complex and troubling. Progressively deeper hues represent the greatest and most problematic rates of change. The deepest blues indicate areas where flooding has been increasing, the deepest reds indicate areas where water losses have been most severe.